This is the only story related achievement that glitched for me. I deleted all my game saves and started a new game and played until i got to the Zero Cool mission, made a save right before starting it just in case it glitched again. Then went through the mission and it popped immediately after i finished the mission. Don`t bother doing the mission in coop with someone that has a save prior to that mission, it will not solve the glitch (at least for me it didn`t). Happy hunting!